The printing system to which this invention is directed and current control systems for the printhead are disclosed in U.S. Pat. No. 4,350,449 to Countryman et al and U.S. Pat. No. 4,345,845 to A. E. Bohnhoff et al, which is herein incorporated by reference. Those patents do not address the spreading of current at electrodes when one or more contiguous electrodes are not driven.
The existence of a current-spreading effect and resulting lighter printing at image edges may be observed from close inspection. U.S. Pat. No. 4,217,480 to F. C. Livermore et al describes such a current-spreading problem and describes the use of a negative-temperature-coefficient resistance to counteract the problem. In contrast, the subject invention employs an interconnection between adjoining electrode drivers.